Drivers Override Safety Features

UI study shows we adapt to protective innovations in ways that put us at risk

By Jennifer Hemmingsen
The Gazette

IOWA CITY - Car safety equipment helps prevent crashes in the short term, but over the long term, driver safety depends on one thing: the driver.

Researchers are learning that drivers sometimes adapt to new technology designed to make them safer in ways that actually might be harmful, said Linda Ng Boyle, assistant professor of mechanical and industrial engineering in the University of Iowa College of Engineering.
Take those variable message signs placed on the side of the road that warn of bad conditions ahead.

Boyle’s research shows signs make drivers slow down at first. But after they think the danger has passed, drivers won’t go back to their normal speed. In fact, they’ll go even faster.

‘‘You’re going faster than you normally would,’’ she said. ‘‘So have we put you in a safer position?’’

Boyle, a human factors researcher in the UI Public Policy Center and faculty director of the Human Factors and Statistical Modeling Lab, studies risks that affect driving.

Yet she says she’s as guilty as anyone. She used to drive a car with a warning light that told her when she ran low on gas. After a while, she started waiting until the light came on to go to the pump.

Then she got a new car that didn’t have the light.

‘‘And because I didn’t get that feedback anymore, I kept running out of gas,’’ she said.

Boyle said transportation studies have shown the same phenomenon with anti-lock brakes. When introduced, they reduced a driver’s likelihood to crash. But once people got used to that protection, crashes increased.

Other technologies to make us safer are being developed. They include sensors that warn drivers when their cars veer off the road or alerts that activate when drivers start to nod off behind the wheel. If the research holds true, our safety will depend on how we adapt.

Boyle recently won a fiveyear, $450,000 National Science Foundation Career Award grant to look more closely at how people respond in unintended ways to technologies. She will focus on adaptive cruise control, a technology being installed on new higher-end cars that automatically slows you down when you get too close to another car.

Boyle wants to know whether drivers using the system pay less attention to cars around them, and what will happen if, for example, someone suddenly cuts in front of them.

A 1977 road safety study found human error was the sole cause in 57 percent of all accidents and a contributing factor in more than 90 percent — and that was before the explosion of cell phones, text messaging and video displays. Other studies have produced similar results.

As many as 80 percent of people on the road think they’re better- than- average drivers, public health researchers have found. Boyle said one of her subjects told her: ‘‘I got into a car accident when I was putting on lipstick because my mom was yelling at me.’’

One of Boyle’s students, Birsen Donmez, a doctoral student in industrial engineering from Turkey, is studying ways to alert drivers distracted by cell phone conversations. She is using an Instrumented Car — a 2002 Ford Taurus equipped with seven cameras, a visual scanner, sensors to track a driver’s response to different driving conditions, a GPS device mounted on the back and a hard drive in the trunk.

Driver studies show that more than half of all accidents are caused by distracted drivers. Donmez said she has found that the more people are made aware of their distraction, the better drivers they become.